Thanks to everyone who posted, very amusing/informative!
One earlier reply mentioned adding a little water to a mix just to loosen it up as it gets close to going off - is this ok to do? I've always understood it wasn't a good idea...This would help me immensely at the moment given the problems I'm having. I've got half a bag left so I'm mixing very small batches. Looks like I'm going to be one tile short due to my fun and games with my cutter (see other post), how annoying is that?!
Adding more water to the mix as its going off will just make it go lumpy . Not something i would advise doing. .